It is becoming possible to connect a variety of consumer electronics and computer peripherals to networks. For example, providing network support for devices such as printers, projectors, scanners, digital cameras and digital video cameras is being considered. It is expected that such network-compatible devices will be connected not only to LANs but also to WANs such as the Internet.
There is growing demand for remote control of these network-compatible devices from portable terminals such as mobile phones and PDAs. In order comply with this demand, it is necessary to assign an IP (Internet Protocol) address to a network-compatible device operated over the Internet and make public the URL (Uniform Resource Locator) or IP address.
With the art described above, anyone who knows the URL or IP address of the network device is capable of operating the device without permission. For example, consider a residence surveillance system constructed according to the prior art described above. With a system of such kind, a large number of unspecified individuals, namely individuals other than the owner of the residence for which the system has been constructed, would be able to observe the conditions around the residence. This would not only constitute an invasion of privacy but could also allow a malicious third party to become aware of the fact that the owner of the residence is away from home. This could not help but encourage burglary.
Thus, a device control system or service that utilizes the Internet is disadvantageous in that an unintended party may use the controlled device without permission owing to the fact that the URL or IP address of the controlled device connected to the Internet is made public.